Cool-down apparatus for cryogenic liquid containers



April 21, 1959 P. c. VANDER-AREND. ETAL 8 COOL-DOWN APPARATUS FORCRYOGENIC LIQUID CONTAINERS Filed Oct. 5. 195a grwc/wtow PETER 0.VIM/DER ARE/VD DOUGLAS MANN United. States P tent COOL-DOWN APPARATUSFOR CRYOGENIC LIQUID CONTAINERS Peter C. Vander Arend, Macungie, Pa.,and Douglas Mann, Boulder, Colo., assignors to the United States ofAmerica as represented by the Secretary of the Navy Application October5, 1956, Serial No. 614,328

4 Claims. (Cl. 62-45) (Granted under Title 35, US. Code (1952), see.266) The invention described herein may be manufactured andused by orfor the Government of the United States of America for governmentalpurposes without the payinent of any royalties thereon or therefor.

This invention relates to cryogenic apparatus, with special reference tomeans for cooling down receptacles for liquid gases, such as thoseofoxygen, nitrogen, helium and hydrogen.

The general arrangement of a storage container for liquefied gasesconsists of a number of concentric shells with a suitable insulationseparating these shells. The inner shell of the container holds theliquefield gases, the outer shell or shells usually serving to confinethe insulating medium. For liquid oxygen, nitrogen or other cryogenicliquids, only two shells are usually employed, while forliquid hydrogenand helium at least three shells are generally used, the outer shell ineach case being at room temperature, and in the three shell type, theintermediate shell being at an intermediate temperature to reduce theheat leak to the liquid in the inner container.

In either type of container, prior to filling the inner shell with thecryogen, it is desirable to cool the container and this is done in thetwo shell type merely by pouring some of the liquefied gas into theinner shell and thus boiling off the liquid. For the hydrogen threeshell type, however, it has been found more efiicient to use two stages;first, cooling down the chamber to the temperature of liquid air, andsecond, cooling the chamber to the liquid hydrogen (or helium)temperature, thus conserving the amount of liquid hydrogen boiled off inthe cooling process.

The above cooling methods have one important disadvantage, very littleuse is made of the cold vapor resulting from the boiling or evaporationstep, practically all of the cooling resulting from heat extraction bythe heat of vaporization of the boiling liquids. The amount of heatwhich may be absorbed by the liquid vapor is very large compared withthe heat of vaporization; and hence it becomes important that this vaporbe utilized to accelerate the cool-down process as well as reduce thecost of the procedure.

An important object of the invention, therefore, is to speed up theabstraction of heat from a container prior to the insertion of liquefiedgases therein.

An object, also, is to reduce the cost of pro-cooling a container forliquefied gases.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Fig. 1 is a plan view, with parts broken away, of a two shell containerfor low temperature liquefied gases; and

Fig. 2 is a perspective, sectional view of the two shell container ofFig. 1, showing the disposition of the inner shell for channelling thegases during the pre-cooling step.

Referring to the figures, the container is indicated generally by thenumeral 10, and is formed of two shells, the outer shell 11 and theinner shell 12. The outer shell 11 includes a central cylindricalsection 13 and end sections 14 and 15, the end sections being in theform of hemispherical members having edges alined and fixed, as bywelding, to the cylinder section ends.

The inner shell 12 closely conforms in contour to the outer shell 11,the chief distinctions being that the central section 16 has a paraxialsection cut out in the base area to form an elongated passageway betweenthe two shells; and the top section 17 is flattened to form at outletmaul: fold. Also, transverse ribs 18 are fixed to the external surfaceof the central section 16 of the inner shell, at spaced intervals alongthe length thereof to form plural channels 19 between the shells,extending from the flat upper plate 17 to shell edges 20 at the base ofthe con tainer on both sides thereof. To facilitate the guiding functionof the channels 19, the inner shell edges 20 are flanged and cut awayopposite each channel end, as at 21, to form guide openings from thespace 22 directly at the container base and between the inner shelledges 20.

Communication to the space 22 from the containerexterior is by means oftube 25, which extends from space 22, at a point above the outer shellwall, vertically through the inner container through the flattened shellof inner shell plate 17 and through outer shell section 13 to a point ofaccess for insertion of liquefied gases. A valve (not shown) is includedin the exposed section of tube 25. Access to the interior of the innershell is by way of the tube 26 attached to flat plate section 17, thistube being provided with valve 27, for venting gases formed duringcontainer filling. Tube 28, connected to the top of container section13, provides a vent during the cool-down operation, a valve 29 beingindicated.

In the operation of the pre-cooling apparatus, a restrictedpredetermined amount of liquefied gas is passed through the tube 25 tospace 22 in the base of the outer container, flowing over this space andthrough channels 21 into the space between the container shells. Theliquid rapidly evaporates, the heat of evaporation extractingconsiderable heat from the container walls, and the highly cooled gasesflowing in part into the inner shell and also in large volume betweenthe shells along the channels 19 to the space above the flattened shellsection 17, where it moves out through tube 28, valve 29 being open.Thus, it is seen that all sections along the inner shell section aresimultaneously cooled by convective flow of the low temperature gases,this cooling effect being directly operative on both shells, which atthe same time are being subjected to heat abstraction through action ofthe heat of vaporization of the liquid. Thus, the container is quicklyand efiiciently cooled by the initial charge of liquefield gases.

A comparison of the described procedure with that where guided vapor isnot used would be of interest at this point. Using a container of 50,000liters capacity and 22,000 pounds weight and assuming a cool-down stepfrom K. to 4 K., a total of 16,500 liters of liquid helium is requiredwhere the liquid is merely dumped within the container, whereas for thesame capacity container but using the shell guides as hereinabovedescribed, only 1250 liters of liquid helium are required for the sametemperature reduction.

It is apparent that the ribs 18, while definitely advantageous insecuring a more uniform cool-down along the container length, are notessential to the specific process. Also, the action is not particularlylimited to container size, the procedure being successfully applicableto large or small units.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

.. I 2,882,694 7 h A 311A cool-down apparatus .for cryogenic containerscomprising a first tubular closed shell for reception of a cold liquid,a second tubular closed shell within said first shell with the outerwall surface ofthe second shell cone forminggenerally to the inner wallsurface of the first shell but having a paraxial passageway along oneside thereof adjacent the first shell, said shells being displaced fromeach other to form an intervening channel space therebetween, a tubeextending fromv said second shell passageway through the opposite wallsof said shells to permit supply of liquid to the container at saidpassageway only, normallyopen vent tubes for each of said shells, andribs formed in the channel space between said shells transversely to thecontainer axis, said ribs extending from said paraxial passageway in thesecond shell on both sides thereof to .a point terminating adjacent butdisplaced from aplane including the container axis and vent tubepassageway for said. outer shell.

2. .The cool-down apparatus as defined in claim 1 with said ribs whichextend from the passageway in said second shell. on both sides thereoflying in a common plane transverse tosaid container axis.

4 .3. The cool-down apparatus as defined in claim 1 with said secondshell flattened lengthwise in the area opposite 4 the shell slot andadjacent the vent passageway of .the'first shell, whereby an enlargedoutlet manifold channel is provided for said channel space.

4. A cool-down apparatus for cryogenic containers comprising a firsttubular closed shell for reception of a cryogen, a second shell withinsaid first shell and forming therewith a channel space, a paraxialpassageway on one side of said second shell, an inlet tube extendingfrom said passageway through the shell walls opposite to saidpassageway, a vent tube for each of said shells, an outlet manifoldextending from end to end between said shells on the side opposite tosaid passageway, and means for dividing said channel space into aplurality of parallel channels transverse to the container axis.

References Cited in the file of this patent UNITED STATES PATENTS662,217 Brady Nov. 20, 1900 1,807,108 Tontet May 26, 1931 1,894,497Rowland Jan. 17, 1933 1,976,688 Dana Oct. 9, 1934 1,998,629 Lagarde Apr.23,1935 2,293,263 Kornemann Aug. 18, 1942

